Merge tag 'dm-4.2-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:

 - revert a request-based DM core change that caused IO latency to
   increase and adversely impact both throughput and system load

 - fix for a use after free bug in DM core's device cleanup

 - a couple DM btree removal fixes (used by dm-thinp)

 - a DM thinp fix for order-5 allocation failure

 - a DM thinp fix to not degrade to read-only metadata mode when in
   out-of-data-space mode for longer than the 'no_space_timeout'

 - fix a long-standing oversight in both dm-thinp and dm-cache by now
   exporting 'needs_check' in status if it was set in metadata

 - fix an embarrassing dm-cache busy-loop that caused worker threads to
   eat cpu even if no IO was actively being issued to the cache device

* tag 'dm-4.2-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm cache: avoid calls to prealloc_free_structs() if possible
  dm cache: avoid preallocation if no work in writeback_some_dirty_blocks()
  dm cache: do not wake_worker() in free_migration()
  dm cache: display 'needs_check' in status if it is set
  dm thin: display 'needs_check' in status if it is set
  dm thin: stay in out-of-data-space mode once no_space_timeout expires
  dm: fix use after free crash due to incorrect cleanup sequence
  Revert "dm: only run the queue on completion if congested or no requests pending"
  dm btree: silence lockdep lock inversion in dm_btree_del()
  dm thin: allocate the cell_sort_array dynamically
  dm btree remove: fix bug in redistribute3

1 files changed, 23 insertions, 15 deletions

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 1b4e1756b169..b680da5d7b93 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -424,7 +424,6 @@ static void free_migration(struct dm_cache_migration *mg)
 		wake_up(&cache->migration_wait);
 
 	mempool_free(mg, cache->migration_pool);
-	wake_worker(cache);
 }
 
 static int prealloc_data_structs(struct cache *cache, struct prealloc *p)
@@ -1947,6 +1946,7 @@ static int commit_if_needed(struct cache *cache)
 
 static void process_deferred_bios(struct cache *cache)
 {
+	bool prealloc_used = false;
 	unsigned long flags;
 	struct bio_list bios;
 	struct bio *bio;
@@ -1981,13 +1981,16 @@ static void process_deferred_bios(struct cache *cache)
 			process_discard_bio(cache, &structs, bio);
 		else
 			process_bio(cache, &structs, bio);
+		prealloc_used = true;
 	}
 
-	prealloc_free_structs(cache, &structs);
+	if (prealloc_used)
+		prealloc_free_structs(cache, &structs);
 }
 
 static void process_deferred_cells(struct cache *cache)
 {
+	bool prealloc_used = false;
 	unsigned long flags;
 	struct dm_bio_prison_cell *cell, *tmp;
 	struct list_head cells;
@@ -2015,9 +2018,11 @@ static void process_deferred_cells(struct cache *cache)
 		}
 
 		process_cell(cache, &structs, cell);
+		prealloc_used = true;
 	}
 
-	prealloc_free_structs(cache, &structs);
+	if (prealloc_used)
+		prealloc_free_structs(cache, &structs);
 }
 
 static void process_deferred_flush_bios(struct cache *cache, bool submit_bios)
@@ -2062,7 +2067,7 @@ static void process_deferred_writethrough_bios(struct cache *cache)
 
 static void writeback_some_dirty_blocks(struct cache *cache)
 {
-	int r = 0;
+	bool prealloc_used = false;
 	dm_oblock_t oblock;
 	dm_cblock_t cblock;
 	struct prealloc structs;
@@ -2072,23 +2077,21 @@ static void writeback_some_dirty_blocks(struct cache *cache)
 	memset(&structs, 0, sizeof(structs));
 
 	while (spare_migration_bandwidth(cache)) {
-		if (prealloc_data_structs(cache, &structs))
-			break;
+		if (policy_writeback_work(cache->policy, &oblock, &cblock, busy))
+			break; /* no work to do */
 
-		r = policy_writeback_work(cache->policy, &oblock, &cblock, busy);
-		if (r)
-			break;
-
-		r = get_cell(cache, oblock, &structs, &old_ocell);
-		if (r) {
+		if (prealloc_data_structs(cache, &structs) ||
+		    get_cell(cache, oblock, &structs, &old_ocell)) {
 			policy_set_dirty(cache->policy, oblock);
 			break;
 		}
 
 		writeback(cache, &structs, oblock, cblock, old_ocell);
+		prealloc_used = true;
 	}
 
-	prealloc_free_structs(cache, &structs);
+	if (prealloc_used)
+		prealloc_free_structs(cache, &structs);
 }
 
 /*----------------------------------------------------------------
@@ -3496,7 +3499,7 @@ static void cache_resume(struct dm_target *ti)
  * <#demotions> <#promotions> <#dirty>
  * <#features> <features>*
  * <#core args> <core args>
- * <policy name> <#policy args> <policy args>* <cache metadata mode>
+ * <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
  */
 static void cache_status(struct dm_target *ti, status_type_t type,
 			 unsigned status_flags, char *result, unsigned maxlen)
@@ -3582,6 +3585,11 @@ static void cache_status(struct dm_target *ti, status_type_t type,
 		else
 			DMEMIT("rw ");
 
+		if (dm_cache_metadata_needs_check(cache->cmd))
+			DMEMIT("needs_check ");
+		else
+			DMEMIT("- ");
+
 		break;
 
 	case STATUSTYPE_TABLE:
@@ -3820,7 +3828,7 @@ static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
 
 static struct target_type cache_target = {
 	.name = "cache",
-	.version = {1, 7, 0},
+	.version = {1, 8, 0},
 	.module = THIS_MODULE,
 	.ctr = cache_ctr,
 	.dtr = cache_dtr,